First you create a proportion (30/100=x/120). After you solve this, next you subtract this answer from 120. Then create a proportion for 40% (40/100=x/120). Then add this number to the first answer you got when you subtracted the answer from your first proportion from 120.
I recommend using desmos if you wanna know what a graph looks like !
Using linear functions, it is found that the two plans cost the same for 5000 minutes of calling.
<h3>What is a linear function?</h3>
A linear function is modeled by:

In which:
- m is the slope, which is the rate of change, that is, by how much y changes when x changes by 1.
- b is the y-intercept, which is the value of y when x = 0.
For Plan A, the cost is of $25 plus an additional $0.09 for each minute of calls, hence the y-intercept is
, the slope is of
, and the function is:

For Plan B, the cost is of $0.14 for each minute of calls, hence the y-intercept is
, the slope is of
, and the function is:

The plans cost the same for x minutes of calling, considering that:





The two plans cost the same for 5000 minutes of calling.
To learn more about linear functions, you can take a look at brainly.com/question/24808124
8 months; $740
75x+140=90x+20
Find x then plug it in to find the cost